package com.common;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.SecureRandom;

public class SecurityUtils {
	/**
	 * 编码格式
	 */
	private static final String ENCODING = "UTF-8";
	/**
	 * 加密算法
	 */
	public static final String KEY_ALGORITHM = "AES";
	/**
	 * 签名算法
	 */
	public static final String SIGN_ALGORITHMS = "SHA1PRNG";

	/**
	 * 加密
	 *
	 * @param content 待加密内容
	 * @param key     加密的密钥
	 * @return
	 */
	public static String encrypt(String content, String key) {
		try {
			KeyGenerator kgen = KeyGenerator.getInstance(KEY_ALGORITHM);
			SecureRandom random = SecureRandom.getInstance(SIGN_ALGORITHMS);
			random.setSeed(key.getBytes(ENCODING));
			kgen.init(128, random);
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec secretKeySpec = new SecretKeySpec(enCodeFormat, KEY_ALGORITHM);
			Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
			byte[] byteContent = content.getBytes(ENCODING);
			cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
			byte[] byteRresult = cipher.doFinal(byteContent);
			StringBuffer sb = new StringBuffer();
			for (int i = 0; i < byteRresult.length; i++) {
				String hex = Integer.toHexString(byteRresult[i] & 0xFF);
				if (hex.length() == 1)
					hex = '0' + hex;
				sb.append(hex.toUpperCase());
			}
			return sb.toString();
		} catch (Exception e) {
			e.toString();
		}
		return null;
	}

	/**
	 * 解密
	 *
	 * @param content 待解密内容
	 * @param key     解密的密钥
	 * @return
	 */
	public static String decrypt(String content, String key) {
		if (content.length() < 1)
			return null;
		byte[] byteRresult = new byte[content.length() / 2];
		for (int i = 0; i < content.length() / 2; i++) {
			int high = Integer.parseInt(content.substring(i * 2, i * 2 + 1), 16);
			int low = Integer.parseInt(content.substring(i * 2 + 1, i * 2 + 2), 16);
			byteRresult[i] = (byte) (high * 16 + low);
		}
		try {
			KeyGenerator kgen = KeyGenerator.getInstance(KEY_ALGORITHM);
			SecureRandom random = SecureRandom.getInstance(SIGN_ALGORITHMS);
			random.setSeed(key.getBytes(ENCODING));
			kgen.init(128, random);
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec secretKeySpec = new SecretKeySpec(enCodeFormat, KEY_ALGORITHM);
			Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
			cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
			byte[] result = cipher.doFinal(byteRresult);
			return new String(result, ENCODING);
		} catch (Exception e) {
			e.toString();
		}
		return null;
	}

}
